An asteroid hurtled through Earth's backyard Friday, coming within an incredible 17,150 miles (27,599 kilometers) and making the closest known flyby for a rock of its size. In a chilling coincidence, a meteor exploded above Russia's Ural Mountains just hours before the asteroid zoomed past the planet.

Scientists the world over, along with NASA, insisted the meteor had nothing to do with the asteroid since they appeared to be traveling in opposite directions. The asteroid is a much more immense object and delighted astronomers in Australia and elsewhere who watched it zip harmlessly through a clear night sky.

''It's on its way out,'' reported Paul Chodas of NASA's Near-Earth Object program at Jet Propulsion Laboratory in California.

Asteroid 2012 DA14, as it's called, came closer to Earth than many communication and weather satellites orbiting 22,300 miles (35,887 kilometers) up. Scientists insisted these, too, would be spared, and they were right.

The asteroid was too small to see with the naked eye even at its closest approach around 2.25 p.m. EST (2025 GMT), over the Indian Ocean near Sumatra.

The best viewing locations, with binoculars and telescopes, were in Asia, Australia and eastern Europe. Even there, all anyone could see was a pinpoint of light as the asteroid buzzed by at 17,400 mph (28,000 kph).

As asteroids go, this one is a shrimp. The one that wiped out the dinosaurs 65 million years ago was 6 miles across. But this rock could still do immense damage if it ever struck given its 143,000-ton heft, releasing the energy equivalent of 2.4 million tons of TNT and wiping out 750 square miles (1,942 square kilometers).

By comparison, NASA estimated that the meteor that exploded over Russia was much smaller – about 49 feet (15 meters) wide and 7,000 tons before it hit the atmosphere, or one-third the size of the passing asteroid.

As for the back-to-back events, "this is indeed very rare and it is historic,'' said Jim Green, NASA's director of planetary science.

"These fireballs happen about once a day or so, but we just don't see them because many of them fall over the ocean or in remote areas. This one was an exception.''

As the countdown for the asteroid's close approach entered the final hours, NASA noted that the path of the meteor appeared to be quite different than that of the asteroid, making the two objects "completely unrelated.'' The meteor seemed to be traveling from north to south,